Evolution Of Avian Migration Research Articles

The evolution of avian migration

The study of avian migration has reached sophisticated levels in many areas, including ecology, behaviour, and physiology. Traditional discussions of the evolution of migration, however, have been compromised for several reasons. Previous ideas concerning the ancestral home of migrant species, southern or northern, and whether a partially migratory stage always precedes a fully migratory stage, were not expressed as testable hypotheses. Plotting migratory behaviour on phylogenetic trees has become commonplace and allows tests of traditional hypotheses. Some of these studies are reviewed, lending some support for almost all of the previous ideas. Although phylogenetic mapping helps to frame questions about the evolution of migration in a testable framework, there are two serious issues. First, experimental and observational studies reveal that the expression of migratory behaviour can change rapidly within a lineage, which can violate assumptions of character mapping. In addition, a species distribution model is used to show that current conditions for obligate migratory populations of the chipping sparrow were much restricted at the Last Glacial Maximum, and that the species might have been considered a partial migrant at that time. The expression of migratory behaviour in an extant species might be an artefact of the current inter-glacial period. Only if the rate of gains and losses of migratory behaviour can be incorporated into a phylogenetic mapping exercise will the actual evolutionary pattern of migration be revealed. For example, reconstruction of the ancestral area and the evolutionary history of migratory categories in a clade of New World warblers depended on the assumptions of character state transitions. A second concern is that the trait ‘migratory’ is too broad for evolutionary analysis and that, if possible, the expression of hyperphagia, Zugunruhe, and navigation could be mapped individually. Loss or suppression of any of these components can lead to sedentary populations, revealing how migratory behaviour can appear and disappear rapidly. A report of low levels of Zugunruhe in a sedentary bird, Saxicola torquata, is reconstructed as derived in a clade of otherwise migratory populations, suggesting that the loss of migration was a result of suppression (but not elimination) of Zugunruhe. When researchers mention the independent origin of migration in a clade, they are most likely referring to the gain or loss of the expression of the ancestral migratory programme, not the de novo evolution of migration per se. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 104, 237–250.

LIFE HISTORY CORRELATES OF ALTERNATIVE MIGRATORY STRATEGIES IN AMERICAN DIPPERS

Partial migration is thought to be a critical step in the evolution of avian migration, but data on the life history correlates of alternative migratory strategies are extremely limited. We have studied a partially migratory population of American Dippers since 1999. This population is composed of sedentary individuals (residents) that maintain the same territory year round and altitudinal migrants that share winter grounds with residents, but move to higher elevations to breed. We used seven years of data on individually marked birds to (1) determine if individuals consistently use the same migratory strategy, (2) determine if offspring have the same strategy as their parents, and (3) estimate reproductive and survival rates of the two migratory strategies. We evaluate hypotheses for the persistence of partial migration and discuss their implication for the evolution of migration in sedentary populations. Individual American Dippers rarely switched migratory strategy (4/169 monitored more than one year). An individual's strategy, however, was not always that of its parents, indicating that, while migratory behavior may have a genetic component, environmental or social conditions probably influence the migratory strategy that an individual adopts. Sedentary dippers consistently had higher annual productivity (approximately 1.4 more fledglings/year) than migratory dippers, but mark-recapture models suggested that migratory dippers may have slightly higher survival than residents (approximately 3.4%). Migrants were estimated to have lower lifetime reproductive success than residents because their higher survival was insufficient to offset their lower productivity. Our data suggest that alternative migratory strategies in American Dippers are unlikely to be a fixed genetic dimorphism that persists because the two strategies have equal fitness, or because the relative fitness of the two strategies fluctuates over time. Migratory strategies in American Dippers are more likely to be condition dependent, and the two strategies persist because migrants "make the best of a bad job" by moving to higher elevations to breed. Because migrants obtained no fitness benefits by moving to seasonal breeding territories, our data are consistent with the hypothesis that migration could evolve in sedentary populations if competition for limited resources forces some individuals to seek breeding opportunities outside their initial range.

Effects of predator landscapes on the evolutionary ecology of routing, timing and molt by long-distance migrants

Raptors have long been known to prey on avianmigrants (Rudebeck 1950, 1951, Dekker 1980), andseveral studies estimate significant mortality rates formigrants (Lindstro¨m 1989, Kerlinger 1989, Mooreet al. 1990, Sillett and Holmes 2002). These findingsamply justify Alerstam and Lindstro¨m’s (1990) identi-fication of safety as one of the prime selective forcesshaping the evolution of avian migration strategies andbehaviour. However, as shown by a survey of recentvolumes on the ecology and evolution of avianmigration, safety has garnered much less interest fromecologists compared to that paid to time and energy,the other selective factors identified by Alerstam andLindstro¨m. Several contributions in ‘Stopover ecologyof Nearctic-Neotropical Migrants’ (Moore 2000)briefly consider predation risk, but only one chapterof 17 (by Moore et al. 1995) in ‘Ecology andManagement of Neotropical Migratory Birds’ (Martinand Finch 1995) even mentions predators. Neither‘The Ecology of Migrant Birds’ (Rappole 1995) nor theedited volume ‘Birds of two worlds: the ecology andevolution of migration’ (Greenberg and Marra 2005)devote any attention to the effects of predators onmigrants, though one chapter in the latter documentswhat is known of raptor migrations. That things may bestarting to change is evidenced by the inclusion of apaper directly addressing this topic (Lind and Cresswell2006) in the most recent symposium published onmigration issues, in the J. Orn., as well as by thepublication of several field experiments (Schmaljohannand Dierschke 2004, Pomeroy et al. 2006).Here we argue that features of migration such astiming and routing are strongly affected by safetyconcerns, and that careful consideration of such canilluminate aspects of migratory ecology. Phenomenasuch as bad weather may also threaten migrant safety,but our interest here is limited to predators. Our thesisis that both density-mediated and trait-mediated effects(see Lind and Cresswell 2005) have profound andpervasive influences on the evolution of avian migra-tion, with the latter being especially significant. Weconsider a number of continental-scale migratoryphenomena and explain how, in contrast to existingexplanatory hypotheses, these can be viewed as tactics toincrease safety.

The Genetics and Evolution of Avian Migration

One of the characteristics of avian migration is its variability within and among species. Variation in migratory behavior, and in physiological and morphological adaptations to migration, is to a large extent due to genetic differences. Comparative studies suggest that migratory behavior has rapidly and independently evolved in different lineages. One reason behind the high potential for de novo evolution of migratory behavior in sedentary populations seems to be the ubiquity of genetic variation for migratory traits in nonmigratory individuals. In resident lineages, a high degree of hidden genetic variation for migratory traits can be maintained because a migratory threshold determines whether migratory behavior is expressed. Genetic correlations among migratory traits and with other traits of the annual cycle are likely to play a major role in determining the rate and direction of evolutionary change.

PHYLOGENETIC TESTS OF HYPOTHESES FOR THE EVOLUTION OF AVIAN MIGRATION: A CASE STUDY USING THE MOTACILLIDAE

Abstract The evolution of avian migration continues to be an intriguing research subject, even though relationships between migration and factors such as seasonality clearly exist. The question remains whether these relationships are evident within phylogenies containing both sedentary and migratory taxa. We explore the evolution of migration in the family Motacillidae by evaluating existing hypotheses for the evolution of migration in a comparative, phylogenetic framework at the interspecific level. Many hypotheses to explain the evolution of avian migration—such as the “evolutionary precursor” hypothesis (Levey and Stiles 1992, Chesser and Levey 1998) and the “stepping-stone” hypothesis (Cox 1968, 1985)—are based on New World migratory systems. The central components of these hypotheses should apply across biogeographic realms (i.e. the Old World), given that seasonality and habitat regimes are similar in the New and Old worlds. Using a molecular phylogeny containing most species in the Motacillidae, we...

POSTGLACIAL POPULATION EXPANSION DRIVES THE EVOLUTION OF LONG-DISTANCE MIGRATION IN A SONGBIRD

The evolution of long-distance migratory behavior from sedentary populations is a central problem in studies of animal migration. Three crucial issues that remain unresolved are: (1) the biotic and abiotic factors promoting evolution of migratory behavior, (2) the geographic origin of ancestral sedentary populations, and (3) the time scale over which migration evolves. We test the role of postglacial population expansions during the Quaternary in driving the evolution of songbird migration against prevailing views favoring the role of intraspecific competition. In contrast to previous attempts to investigate these questions using interspecific phylogenies, we adopt an intraspecific approach and examine the phylogeography of a North American songbird, the chipping sparrow (Spizella passerina), which exhibits both long-distance migratory behavior in temperate North America and sedentary behavior in Mexico and Central America. We show that migratory populations descend from sedentary populations in southern Mexico and that migration has evolved as a result of a northward population expansion into temperate North America since the last glacial maximum 18,000 years ago. Migration appears to have evolved rapidly in some species as populations colonized areas of high seasonality in the temperate zone. The phylogeography of the yellow-eyed junco (Junco phaeonotus), a strictly sedentary species, provides a null model supporting the view that northward range expansions were driven solely by environmental factors and not by a predisposition to evolve migratory behavior. These results provide the strongest evidence to date that historical climate patterns can drive the rapid evolution of avian migration in natural populations, and they suggest a general mechanism for the repeated evolution of migration within and across bird lineages.

An integrative framework for understanding the origin and evolution of avian migration

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